class ShortInputException(Exception):
    '''一个由用户自定义的异常类'''
    def __init__(self, length, atleast):
        Exception.__init__(self)
        self.length = length
        self.atleast = atleast
    
try:
    text = input("Enter something -->")
    if len(text) < 3:
        raise ShortInputException(len(text), 3)
except EOFError:
    print('Why did you do an EOF on me?')
except ShortInputException as ex:
    print('ShortInputException: The input was ' + '{0} long,excepted at least {1}'.format(ex.length, ex.atleast) )
else:
    print('No exceptions was raised.')